Supersonic flow deflector and silencer

ABSTRACT

A super-sonic flow deflector for deflection of under-expanded gas flow at an angle as great as the exit angle of the deflector surface. A scroll container accompanies said deflector to act as a collector for the exhaust gases after deflection.

limited States Patent Cox et al. [4 1 Sept. 18, 11973 1 SUPERSONIC FLOWDEFLECTOR AND 916,885 3/1909 Maxim 89/14 1) SILENCER 2,449,571 9/1948Walker 89/14 D 956,717 5/1910 Moore 89/14 D [75] Inventors: Lyndon S.Cox, Silver Spring, Md.; Chris E. Spyropoulos, Washington, PrimaryExaminer-Benjamin A. Borchelt [73] Assignee: The United States ofAmerica as Assistant Examiner-Hif represented by the Secretary of the y-"y sal'agovltz et Army, Washington, D.C.

[22] Filed: Dec. 27, 1971 21 Appl. No.: 211,996 57 ABSTRACT [52] US. Cl89/14 D A p rn fl deflector f r efl i n f under- [51] Int. Cl F4lf 17/12e pa ed gas flow at an angle as great as the exit angle [58] Field ofSearch 89/ 14 D, 14 C, 14 R of the deflector surface A ll c n in rmpanies said deflector to act as a collector for the exhaust ReferencesCited gases after deflection.

UNITED STATES PATENTS 1,021,742 3/1912 Moore 89/14 D 3 Claims, 3 DrawingFigures Pmemzusrrw 3,759,134

FIG I F IG 2 39 FIG 3 INVENTORS LYNDON S. COX, CHRIS E. SPYROPOULOS byHARRY M SARAGOVITZ EDWARD J. KELL)? HERBERT BERL,

and SAUL ELBAUM their ATTORNEYS SUPERSONIC FLOW DEFLECTOR AND SILENCERThe invention herein described may be manufactured, used and licensed byor for the United States Government for governmental purposes withoutthe payment to us of any royalty thereon.

This invention relates to a unique supersonic flow deflector andsilencer. The silencing function has an application to quieting ofmuzzle blast when used in weapons.

The immediate application of the instant invention is in the field ofweaponry where several problems are encountered and caused by muzzleblasts. One of these problems is the obscuration of the line of sight bydirt or dust raised from the ground by the muzzle blast.

Another problem caused by muzzle blast is the disclosure of the positionresulting from movement of foliage near the muzzle under the influenceof the muzzle blast.

Still another problem is the oscillation of the barrel from muzzle jumpor vertical movement of the muzzle relative to the breech of the barrel.

Other problems are damage to nearby structures from impingement of thehigh velocity flow of the muzzle blast and exposure of the shooter oroverhang of barrel from protective structure, such as sandbags,resulting from the need for clearance to avoid the above problems.

Also, when a weapon is used in an aircraft there is a need to protectthe air frame from the blast pressure.

Many solutions have been proposed and some employed to minimize theabove problems. Some of those devices proposed have included a series ofvanes by which the muzzle blast is deflected, while still others useports in an enclosure to direct the muzzle blast.

Other prior devices use a simple slot cut in the end of an extensionportion to roughly allow the gas to escape prior to exit of the slug orbullet.

None of these prior art devices function with a high degree ofefficiency, which is one of the objects of the present invention. Theinstant invention provides a means of producing a controlled deflectionby utilizing a compact addition on the barrel of the weapon.

Accordingly, one object of this invention is to provide an improvedsupersonic flow deflector.

Another object of this invention is to provide an improved muzzle blastdeflector for use on weapons.

A still further object of this invention is to provide a muzzle blastdeflection silencer for use in weapons. These and other objects of theinvention will become apparent when reference is had to the accompanyingspecification and drawings in which:

FIG. 1 is a sectional diagrammatic view of the end of a conventionalweapon barrel;

FIG. 2 is a sectional diagrammatic view of a weapon barrel employing thesupersonic flow deflector of this invention, and

FIG. 3 is a sectional diagrammatic view ofa weapon barrel employing boththe supersonic flow deflector concept and the blast deflection silencer.

Referring now to FIG. 1, there is shown a conventional rifle barrelhaving a bore or passage Ill and an end surface 12. It is noted that endsurface 12 is generally perpendicular to the circumference of barrel I0.When the projectile is fired through passage lit, the muzzle blast takeson a shape generally designated by arrows l3, l4 and 15. As noted, themuzzle blast is supersonic flow within a shock bottle defined by anoblique shock as at 113 and w. This conventional form of muzzle blastlends itself to all the problems enumerated beforehand.

The deflector comprising the instant invention is shown in FIG. 2 and isemployed on a barrel 2 11) having a passage Zil. The deflector comprisesan extending portion 23 having a curved concave surface 241. It is notedthat the tip of portion 23) does not interfere with the smooth passageof a projectile exiting from passage 2ll. Opposite portion 23 has avertical end face 22 such as in conventional weapons. A projectile firedfrom passage M will cause a muzzle gas flow to bend and be shaped in thedirection shown by arrows 25, 26, 27 and 28. As noted, surface 243 bendsone portion of muzzle gas flow downwardly as at 25 to a point near 2%where it effects the lower portion of the supersonic flow. The member 23also referred to as a curved lip on one side of the muzzle changes theshoclt bottle shape resulting from a conventional weapon such as inlFllG. ll.

When the pressure ratio across the orifice of the passage is muchgreater than required for sonic flow velocity, as in the case with mostweapons, a shock bottle develops as is shown in FIG. ll. Normally theintroduction of a solid surface within the shock bottle and outside theprojected area of the passage or nozzle does not strongly affect flowacross the center line. However, when the momentum of flowing gas on oneside is turned, as in FIG. 2, and made to re-enter the flow within theshock bottle, the flow of the complete shock bottle can be affected.While sub-sonic flow deflection results from viscous forces as well,supersonic flow deflection results from momentum interactions. The flowdeflector can be used to deflect the shock bottle from a gun muzzle, aspray nozzle of any other application in which the projection of thenozzle must remain clear. The deflection of gases as just described canbe used to provide a corrective force to the muzzle of a weapon as ameans of stabilizing the weapon during automatic firing. Weapons underautomatic fire are known to vary their elevation and have a tendency tocreep upwards.

The concept of the instant curved lip deflector is predicted upon anunder-expanded jet column which is normal for muzzle blast. The gasmolecules leaving the muzzle are at super sonic velocity and followpaths, as shown in FIGS. 11 and 2, radiating from the muzzle. When thesemolecules encounter fluid at sub-sonic .velocity, there is a multiplecollision deceleration of the molecules generating an abruptvelocity-temperaturedensity gradiant or shock. If the moleculesencounter a solid surface, they rebound from that surface. if therebound velocity is counter to the incident velocity, the shock will beproduced upstream from the solid body. However, if the direction of therebound velocity is within 9tlt of the incident velocity, as in the caseof the instant invention, a turning of the flow will result from theensuing collisions. The use of the concave, curved lip to deflect themuzzle blast flow is based upon the above concept combined with the needto inject the redirected flow into the undisturbed part of the muzzleblast in order to provide transverse momentum in the flow forming theshoclt bottle.

A continuation of a second deflecting vane to form a scroll case can beused for form a silencer. Such a silencer is shown in lFlG. 3.

F IG. 3 shows a means for diverting and collecting the flow from asupersonic under-expanded jet such as that formed by exhaustingpropelling gas from a weapon. This method may be used to silence theweapon and/or for collection of the propellant gas for use as a powersource. FIG. 3 shows a weapon muzzle 30 having a bore or passage 31 anda curved deflecting lip 33 having a concave curved surface 34 and an endportion 38. The remaining portion of the muzzle 30 can be flat as at 32.Extending down from the lower portion of muzzle 30 is a support member35 in which is secured a collecting lip 36 which terminates in an endportion 37 and a containing curved member 43 terminating in a lipportion 39. It will be noted that the end portion 38 of lip member 33and end portion 37 of collecting lip 36 are not in the area of theprojected bore or passage. In other words, both lips leave sufflcientroom for a projectile to exit from a general area of the muzzle anddeflector silencer.

The inclusion of the collecting lip in containing portion calls forcollection of a muzzle gas flow after being deflected by portion 33.Such a collection of muzzle gas flow provides for velocity, pressure andtemperature losses within lip 36, before gas discharge. Such a lossshould greatly reduce the sound pressure level of the muzzle blastover-pressure waves. The portion 43 and lip 36 form a scroll case. Thisoffers an advantage over conventional and current types of silencerswhich allow a portion of the higher pressure propellant gas to exhaustimmediately following exit of the bullet from the silencer. The size anddepth of the container area can be determined from knowledge of thepropellant gas pressure at the muzzle of the weapon immediately prior toshot ejection.

Thus it is seen a novel muzzle blast deflector and silencer have beenprovided which do not affect performance of a projectile forced from abore or passage of a weapon and which further work at full efficiency inobviating the basis for most of the common problems encountered withmuzzle blast including noise.

While only one embodiment of the invention herein disclosed has beenshown and described, it will be obvious to those of ordinary skill inthe art that many changes and modifications may be made withoutdeparting from the scope of the intended claims in which:

We claim:

1. A combination of muzzle and flow deflector, said muzzle having athrough bore therein, said flow deflector comprising a member mounted onthe end of said muzzle and extending in front of the end of said muzzle,a portion of said member between the end of said bore and the end ofsaid member having a concave surface which begins and ends in a planeparallel to said bore to effect deflection of a shock bottle normallycaused by supersonic exhaust flow across the path of said bore.

2. A combination as in claim 1 further including a collecting means forsaid exhaust gases.

3. A combination as in claim 2 wherein said collecting means comprises ascroll container attached to said muzzle on the side opposite saiddeflector.

1. A combination of muzzle and flow deflector, said muzzle having athrough bore therein, said flow deflector comprising a member mounted onthe end of said muzzle and extending in front of the end of said muzzle,a portion of said member between the end of said bore and the end ofsaid member having a concave surface which begins and ends in a planeparallel to said bore to effect deflection of a shock bottle normallycaused by supersonic exhaust flow across the path of said bore.
 2. Acombination as in claim 1 further including a collecting means for saidexhaust gases.
 3. A combination as in claim 2 wherein said collectingmeans comprises a scroll container attached to said muzzle on the sideopposite said deflector.